The imperial roots of global trade

Throughout history empires facilitated trade within their territories by building and securing trade and migration routes, and by imposing common norms, languages, religions, and legal systems, all of which led to the accumulation of imperial capital. In this paper, we collect novel data on the rise and fall of empires over the last 5000 years, construct a measure of accumulated imperial capital between countries, and estimate its relationship with trade patterns today. Our measure of imperial capital has a positive and significant effect on trade beyond potential historical legacies such as sharing a language, a religion, a legal system, or links via natural trade and invasion routes. This suggests a persistent and previously unexplored influence of long-gone empires on current trade.